Field
The invention relates to a support for laser cutting of a circuit board.
Description of the Related Art
Circuit board material, such as FR4 circuit board, may be cut by directing laser-generated optical energy onto a circuit board at a power necessary for cutting. Laser radiation is focused onto a circuit board as a small point, whereby in the focal point area the circuit-board substance heats intensely and detaches. Detachment may result from melting, burning, evaporating or the like. Detachment may be enhanced by pressurized air or gas, for instance. Laser cutting allows board parts of electronic circuitry, printed or to be printed on a circuit board module, to be detached from a large circuit board and each circuit board part may be shaped to have a desired form. Each circuit board part may comprise the same electronic circuit, or different circuit board parts may comprise different electronic circuits. Laser cutting provides a clean and precise cut on the circuit board without fouling and wearing a cutting edge.
For cutting, the circuit board is placed on a support, which may be product-specific for each circuit board part. As the support is shaped according to a board part to be produced, laser radiation does not hit the support, and thus damage to the support is avoided.
Attempts have been made to avoid damages caused by laser radiation to the support by employing a belt or slat-type conveyor support, which does not come into contact with the circuit board at the focal point of laser radiation. It is possible to implement the solution, for instance, by means of three rolls such that the middle roll is on the support, and lower than the other two rolls, whereby the roll protects the support while the roll and support location further off the focal point reduces the laser radiation force exerted thereon per surface area unit.
Laser cutting of circuit boards poses problems, however. A problem with a product-specific support solution is that each circuit board to be produced must have a specific support, which makes the cutting arrangement complicated, expensive and prone to fault situations. In the belt and slat-type conveyor, where the support does not come into contact with the circuit board, the problem is that roll locations must be changed along with laser radiation focusing, when the circuit board is being cut. In that case the circuit board may move and the laser radiation may hit a point other than intended. Furthermore, because it is difficult to make the rolls very small, and they do not permit formation of a narrow slit equal to the focal point of laser radiation, the circuit board to be cut may bend at the cutting point and thus becomes off focus, which distorts the cutting direction and deteriorates both the alignment and the cut. Thus there is a need to develop a support to be used in laser cutting.